Marketable Securities - Unrestricted Marketable Securities-Unrealized Losses (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013 investment
Schedule of Available-for-sale Securities [Line Items]
Total number in loss position (investments)	2
Less than twelve months - fair values	$ 16,843
Less than twelve months - unrealized losses	(490)
Twelve months or greater - fair values	0
Twelve months or greater - unrealized losses	0
Total Fair Value	16,843
Total Unrealized Losses	(490)
Mutual Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Total number in loss position (investments)	2
Less than twelve months - fair values	16,843
Less than twelve months - unrealized losses	(490)
Twelve months or greater - fair values	0
Twelve months or greater - unrealized losses	0
Total Fair Value	16,843
Total Unrealized Losses	$ (490)